- We describe the occurrence of a nephrotic syndrome in association with transitional cell carcinoma of the bladder. The proteinuria disappeared several weeks after removal of the tumor. Light and electron microscopy were compatible with a minimal-change lesion, but immunofluorescence showed linear immunoglobulin deposition. Immunoglobulins eluted from the tumor reacted specifically with the kidney and vice versa. We conclude that antibody formation against a specific component of basement membrane common to both kidney and tumor gave rise to the nephropathy in this case.